This case, formerly present in Juralic, had
largely died out in early times, but remains fossilised in a
few set expressions in Atlantean as well as Yalland. In Atlantean, it
originally involved the interpolation of -ET- between the root ending
and the suffix. (See the section on Juralic: Historical grammar of Juralic languages,2, pronouns, adjectives and nouns).

Examples are:
THETTETO, from THETTO (brother), meaning "brother and sister".
NUMETO, from NUMO (eye), meaning " a pair of eyes". (This also
survived in Yalland: NOIMOI (eye) and NOIMIDOI (pair of eyes).
THUYETA, from THUYE (wind) meaning the "Divine Winds", ie:
winds which were believed to be gods.

2. Plural endings in -AI.

-I: was the original Juralic plural
ending, which died out in favour of -IX in Atlantean. Traces of it
remain in certain nouns with irregular declensions, eg:

The vocative case had been subsumed into the
nominative very early on, but a few examples of the vocative singular
case survived for declension 1 nouns. These had the ending -A (from
Juralic -A:
One example is the vocative singular of DAO (god), which was DA (O god!)

4. The locative case

The true successor of the Juralic locative
singular ending -SSE was -S in Atlamtean, but this had been replaced in
early Atlantean by -SIL from the preposition SIL, meaning
"in".

However, the old ending survived in Classical
Atlantean in a few set expressions: